From: "Terrence R. Redding, Ph.D." <tredding@mac.com>
Date: September 29, 2009 12:37:02 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: [Astro_IIDC] Re: [IOTAoccultations] Video Recording planning and preprations for the LCROSS impact plume
Milton, this is all very helpful.
For me in West Pam Beach, the sun will be at 3 degrees and the sky will be brightening rapidly. So there is little hope I will be able to detect anything. But I still plan to try.
I have the Tele Vue Powermate 2.5X and 5.0X so I will be using probably the 2.5X on the 14" scope and the 5X on the 80 mm scope.
Terry - W6LMJ - 14.287
Terrence R. Redding, Ph.D.
Redding Observatory South, West Palm Beach, Florida
http://olt.net/learningstyle/Site_2/Learning_Style_Research.html
How do amateur astronomers learn?
American Association of Variable Star
Observers (AAVSO): RTN http://www.aavso.org/
On Sep 29, 2009, at 1:26 PM, Milton Aupperle wrote:
Hi Terrence;
See:
http://lcross.arc.nasa.gov/observation.htm
and more recently:
http://www.nasa.gov/mission_pages/LCROSS/main/rss_feed_collection_archive_1.html
for details. They changed which crater they will hit (switching to Cabeus proper isntead of Cabeus A) on September 28 too.
As to picking anything, It's pretty doubtful.
The previous impact event of kaguya was only captured using the Anglo-Australian monster big professional scopes (I think it's 3.92 meter aperture) and completely in the narrowband infrared with 1 second exposures and got 2 frames. Also that impact was in the dark terminator and plume showed up against the black shadowed space.
http://www.space.com/news/090610-kaguya-moon-impact.html
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44977
This time around it's not clear if we will see anything above the horizon at all. That area is fully illuminated and a long way from the east terminator. To separate from the lunar surface, the it's going to have to be kilometers high up plume or it won't make it over the rim. With my C8 at 4 meter focal length, 1 kilometer is about 2 pixels on my Flea or Grasshopper cameras.
I put together an image of what the moon will look like from Calgary at 5:30 am MST October 9th :
http://groups.yahoo.com/group/Astro_IIDC/files/Other/Cabeus_Impact_MJA.jpg
and labelled some of the craters, including Cabeus. For me the moon will be at zenith then and about 64° above the horizon, so it's as good as it gets for observing. I also put up FOV indicators to give you some idea of scale too. Those pink boxes are what I get with the Flea (640x480 7.4 micron pixels) and Grasshopper (1384x1036 6.7 micron pixels) in arc minutes using a 2x barlow on my C8 (effectively 4,000 mm focal length).
To even begin to resolve it, your going to need a 2x to 5x barlow, and that means longer exposures which increase the square of the magnification. So if you shoot with a 2x barlow, then you need 4x the exposure time and with a 5x barlow, you need 25 times as much exposure time.
HTH..
Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1106 - 428 Chaparral Ravine View SE.
Calgary Alberta T2X 0A5
1-(403)-453-1624
On 28-Sep-09, at 8:04 PM, Terrence Redding wrote:
Tom, I am glad you have started this thread. I too plan to record this event and have the same concerns.
What would be the best filter to use from the east coast of the USA?
How aperture dependent is this event?
I assume most of us will attempt at 30 FPS. But would 60 or 120 FPS be better? I have a firewire camera capable of 120 FPS recording direct to disk.
What would the optimum setup be for a 3", 4", 5", 6", or larger scope? What would the minimum scope be for visual observation?
Should one consider a blue filter, red filter, or an infrared cut filter as optimum. If we don't have an infrared cut filter what other filters should be considered?
